This invention relates generally to vehicle rear vision systems for providing drivers with a view rearwardly of the vehicle. The invention may find application with optical rearview mirror assemblies and with solid-state-imaging arrays which capture images rearwardly of the vehicle for display by a display device.
With the advent of electro-optic mirror systems, in which an electro-optic reflectance element is driven to a partial reflectance level by a control module which is responsive to light levels in and around the vehicle, the vehicle rearview mirror has become an electronic assembly. Additional elements, such as motorized positioning devices, or actuators, for the mirror as well as mirror heaters, further contribute to the electrical functions performed by a mirror assembly. These functions require a one-way flow of control information to the mirror assembly. More recent features, such as multiple mirror position memory, require a two-way communication flow. The memory mirror assembly includes a position encoder which communicates the position of the mirror to a memory controller, typically located remotely from the mirror, such as at the vehicle dash. Other two-way communication flows are required by the addition of other features in the rearview mirror, such as keyless entry systems and the like. Other features are being added to vehicle mirrors, in general, and exterior mirrors, in particular, such as remote-actuated exterior vehicle security lights and signal lights, such as disclosed in commonly assigned U.S. Pat. Nos. 5,371,659 and 5,497,305 for REMOTE ACTUATED EXTERIOR VEHICLE SECURITY LIGHT; global positioning system antennas and/or receivers, as disclosed in commonly assigned U.S. International Application W09721127 published Dec. 6, 1996, by Roger L. Veldman and Desmond J. O""Farrell for a VEHICLE GLOBAL POSITIONING SYSTEM NAVIGATIONAL AID; and blind spot detection systems, such as disclosed in U.S. patent application Ser. No. 60/013,941 filed Mar. 22, 1996, by Kenneth (NMI) Schofield for PROXIMITY DETECTION OF OBJECTS IN AND AROUND A VEHICLE, the disclosures of which are hereby incorporated herein by reference. Various other electronic functions, including heading sensors, better known as electronic compasses, intrusion detection and other security systems, antennas for intelligent vehicle highway systems (IVHS), as well as various transmitting and/or receiving antennas and/or systems including garage door openers, cellular telephones, radios, and the like are candidates for positioning within a mirror assembly.
Even with the moderate level of electrification of present vehicle mirror assemblies, it is not uncommon to require as many as 20 wire leads extending to the exterior mirror assemblies. This creates the problem of guiding the wire harness, including a connector, through the door panel. Additionally, the wiring harness adds weight to the vehicle and greatly increases the labor assembly time of the vehicle.
It has been proposed to replace the exterior mirror system of a vehicle with solid-state-imaging arrays which capture images rearwardly of the vehicle for display by a display device on or near the vehicle dash. One such system is disclosed in commonly assigned U.S. Pat. No. 5,670,935 issued to Kenneth (NMI) Schofield, Mark L. Larson and Keith J. Vadas for a REARVIEW VISIONSYSTEM FOR VEHICLE INCLUDING PANORAMIC VIEW, the disclosure of which is hereby incorporated herein by reference. In such a rearview vision system, the solid-state-imaging device may be positioned in a housing in the approximate vicinity of present exterior rearview mirrors. As such, it can be expected that many of the electrical functions being placed in the housing of existing and proposed rearview mirror assemblies will be placed in the housing of the solid-state-imaging array in such system.
The increase in electronic functions being performed through the vehicle rearview assembly increasing involves communication with other portions of the vehicle. For example, global positioning system (GPS) functions and intelligent vehicle highway system (IVHS) functions may interact with other modules controlling vehicle navigation and the like. A headlamp control of the type disclosed in commonly assigned U.S. Pat. No. 5,715,093 issued to Kenneth L. Schierbeek and Niall R. Lynam, for an AUTOMATIC REARVIEW MIRROR SYSTEM WITH AUTOMATIC HEADLIGHT ACTIVATION, the disclosure of which is hereby incorporated herein by reference, utilizes common light sensors for activating the vehicle""s headlights and establishing a partial reflectance level for the electro-optic mirror element. Such feature requires interaction with a headlamp module. Keyless entry systems may interact with the vehicle door locks, as well as interior lighting systems. Blind spot detection, intrusion detection, as well as numerous other functions, may involve interaction with various modules associated with the vehicle dash. Therefore, the vehicle mirror system is becoming more integrated with the rest of the vehicle electronics. A variety of other functions can be integrated into the interior or exterior mirror housing. For example, an electronically trainable garage door opener may be included, such as is described in U.S. Pat. No. 5,479,155 issued to Zeinstra et al.
In order to minimize hardware cost and overhead, as well as provide flexibility for expansion and technological advancements in vehicle electronics, vehicles are increasingly being equipped with serial data communication networks. Such networks include a bidirectional serial multiplex communication link over a bus among a plurality of control modules, each containing a microprocessor or microcomputer. Messages are transmitted asynchronously with priorities assigned to particular messages. For example, messages which require immediate access to the bus for safety reasons are provided top priority, with messages that require prompt action in order to prevent severe mechanical damage to the vehicle provided with a lesser priority but a higher priority than messages that affect the economical or efficient operation of the vehicle. The protocol of the system provides that higher priority messages are communicated without delay while lower priority messages await communication of higher priority messages. An industry standard for such serial data communication network is SAEJ1708 published October 1993.
Functions associated with rearview mirror assemblies have traditionally not been included on the vehicle communication network. Almost all of the traditional mirror functions would be assigned lowest priority and would, therefore, have to await transmission of higher priority messages. Therefore, the traditional approach has been to provide dedicated hardware interconnects between devices located in the rearview mirror assemblies and external devices, such as power sources, switches, controls, and the like. One solution is proposed in U.S. Pat. No. 5,196,965 entitled REARVIEW UNIT FOR MOTOR VEHICLES in which a multiplex data system communicates information between a control unit and at least one exterior rearview mirror. While such system reduces the wire count extending through the door, or doors, to the exterior mirrors, it tails to fully integrate functions associated with the mirror assemblies with the remaining electronic assemblies of the vehicle.
Vehicle memory mirror systems include encoders for monitoring the position of each mirror element with respect to typically two axes and a positioning device, such as an actuator, for selectively positioning the mirror element with respect to those axes. A control unit, typically located in and about the dash or in the door assembly, is capable of storing multiple data sets, each of which establishes a particular position of one or more of the vehicle""s mirror elements. In this manner, when a different driver operates the vehicle, the data set associated with the driver is retrieved and utilized to position the mirror element, or elements, according to that data set. In order to do so, it is necessary to have information regarding the actual position of the mirror, which is provided by the position encoder, in order to enable the control to properly position the mirror element or elements. Such memory mirror systems further contribute to the wiring problem associated with rearview mirrors. The signals from the position encoder require additional wire leads, and all mirror assemblies included in the system must be wired back to a processor which is typically located in the dash. Furthermore, a user input device, such as a joystick, must be provided for use with each of the mirror elements of the memory mirror system in order to allow each driver to adjust each mirror element and store the position of that mirror element for that driver. This is a rather cumbersome process that can be distractive if performed while the vehicle is being operated.
The present invention is directed to a vehicle rear vision system having at least two rearview assemblies. Each of the rearview assemblies includes an image transfer device for transferring images rearwardly of the vehicle in order to be observable by a vehicle driver and a housing for the image transfer device. According to an aspect of the invention, a rear vision communication system provides communication between the rearview assemblies. Additionally, the rear vision communication system includes a communication link with the vehicle communication network. The rear vision communication system preferably includes control modules in each of the rearview assemblies which are interconnected by a communication channel. The image transfer device may be a mirror element, preferably an electro-optic mirror element and, most preferably, an electrochromic mirror element. Alternatively, the mirror element could be a chrome mirror or a standard silvered day/night prismatic mirror, especially for the interior rearview assembly. Alternatively, the image transfer device may be a solid-state-imaging array which captures images rearwardly of the vehicle for display by a display device.
According to a somewhat more specific aspect of the invention, a vehicle rear vision system includes an interior rearview mirror assembly and at least one exterior rearview mirror assembly, each including an electro-optic reflectance element and a housing for the reflectance element. The interior rearview mirror assembly includes a microprocessor-based control having a control channel to establish a partial reflectance level of the associated electro-optic reflectance element. The exterior rearview mirror assembly includes a microprocessor-based control having a first control channel to establish a partial reflectance level of the associated electro-optic reflectance element, a second control channel to selectively activate a heater element in heat transfer association with the associated electro-optic reflectance element, a third control channel to operate a positioning device for the associated electro-optic reflection element, and a fourth control channel for receiving positional data from an encoder coupled with the associated electro-optic reflectance element. A communication channel is provided interconnecting the microprocessor-based controls, defining a rear vision communication network. At least one of the microprocessor-based controls includes a hardware node configured to interconnect with the vehicle communication network. That particular microprocessor-based control is programmed to format messages for the vehicle communication network and decode messages from the vehicle communication network.
Such a vehicle rear vision system, including a rear vision communication network, enhances the functionality of the vehicle rear vision system because the control commands for strictly local functions associated with the rear vision system are handled without requiring access to the vehicle communication network. In this manner, the rear vision system functions do not need to compete with higher priority functions of the vehicle communication network, such as automatic braking systems, air bag systems, and the like. This additionally reduces the load on the vehicle communication network by reducing the number of messages processed on that network. A vehicle rear vision system, according to the invention, provides connectivity between functions carried out by the vehicle rear vision system and other portions of the vehicle electronic system. This is provided by the communication link between the rear vision communication network and the vehicle communication network. This is accomplished without requiring a link between each rearview assembly control module and the vehicle communication network. Not only does this enhance the functionality of the vehicle rear vision system and the vehicle communication network, it reduces system hardware and software expense because most rearview assemblies require only a communication module and associated software. Only one of the rearview assemblies must be fully compatible with the vehicle communication network. A vehicle rear vision system, according to the invention, also significantly reduces the number of wire runs to each rearview assembly which reduces weight and cost while concurrently facilitating enhancement in reliability.
A vehicle rear vision system, according to yet an additional aspect of the invention, includes a plurality of rearview mirror assemblies, each including a reflective element, an actuator, which adjustably positions the reflective element about at least one axis, and a position encoder, which monitors the position of the reflective element with respect to that axis. A control is provided which is responsive to the encoder for each mirror assembly in order to supply positioning signals to the actuator for that mirror assembly. The positioning signals are a function of the position of the reflective element of that mirror assembly. The positioning signals are additionally a function of the position of the reflective element of at least one other of the mirror assemblies. Because each mirror reflective element is positioned by its actuator as a function not only of its own position, but the position of one or more of the other mirror reflective elements, a change in position of one reflective element results in a repositioning of all of the reflective elements controlled in this manner. This interactive dynamic memory mirror system is capable of defining a unique position, associated with the driver""s eyes, which is targeted by all mirrors as a viewing point. As the viewing point changes, the position of the mirrors change in unison. Thus, this aspect of the invention provides an active closed-loop system which correlates the position of all mirror reflective elements. The user viewing point may be established by a conventional user input device, such as a joystick, such that manipulation of the joystick allows the user to simultaneously reposition all of the system mirror elements. This reduces the amount of manipulation which must be carried out by the driver to position the mirrors according to the viewing point of that driver. Additionally, a reduction in system hardware may be effected because only one joystick circuit is required. This aspect of the invention also comprehends the elimination of the joystick altogether by allowing the driver to position one mirror reflective element, such as the interior mirror reflective element, by hand with the control interactively repositioning the other mirror elements in response to the manual repositioning of the mirror reflective element. Alternatively, the location of the driver""s eyes and, therefore, the optimum viewing point for each of the mirror elements, may be measured by machine vision techniques using solid-state-imaging arrays and image recognition software known in the art.
A dynamic interactive memory mirror system, according to this aspect of the invention, may additionally include a xe2x80x9czeroingxe2x80x9d function in order to allow the driver to establish an initial positional relationship of the mirror elements that is more suitable to that driver. This would be particularly advantageous for drivers who utilize unconventional seating postures. The positional relationships of the mirror elements may be fixed to a more desirable viewing angle with respect to the vehicle than is typically utilized by most drivers. For example, it is known that most drivers align exterior rearview mirrors in order to capture at least a portion of the side of the vehicle in the image viewed in the mirror element by the driver. However, a mirror element orientation which extends angularly more outwardly of the vehicle may be more optimal for capturing objects in the driver""s traditional blind spot. By pre-establishing positional relationships between the mirror elements, it may be possible to position the exterior mirrors in more appropriate positions with respect to the position of the interior mirror than that which would be typically set by the driver utilizing conventional norms. These and other objects, advantages, and features of this invention will become apparent upon review of the following specification in conjunction with the drawings.